Acrylic film and laminates comprising the same

ABSTRACT

To provide an acrylic film, composed of a resin composition (C) that includes an acrylic graft copolymer (A) containing an acrylic ester rubber-like polymer and a methacrylic polymer (B) containing 80% by weight or more of methyl methacrylate, wherein (1) the content of the acrylic ester rubber-like polymer in the resin composition (C) is 5% by weight or more and 30% by weight or less, (2) the average particle size of the acrylic ester rubber-like polymer is 500 to 2000 Å, (3) the relationship between the average particle size d (Å) of the acrylic ester rubber-like polymer and the amount w (% by weight) of crosslinking agent used in the acrylic ester rubber-like polymer satisfies the following equation: 0.002d≦w≦0.005d, (4) the graft ratio of the acrylic graft copolymer (A) is 30% or more and 200% or less, and (5) the reduced viscosity of methyl ethyl ketone soluble matter in the resin composition (C) is 0.2 to 0.8 dl/g.

TECHNICAL FIELD

The present invention relates to a special acrylic film and an acrylicfilm laminate, in particular to an acrylic film laminate produced byinjection molding.

BACKGROUND ART

Methods for decoration of the surface of plastic or metal parts include,for example, a direct printing process and a decalcomania process.However, the direct printing process has a problem of being unsuitablefor molded products having a complex shape, whereas the decalcomaniaprocess has a problem of being costly. In the meantime, there aremethods for decoration of the surface of plastic or metal products atlow costs: for example, a film insert molding process in which a baseresin is injection molded while a film of acrylic resin etc. having beenshaped by vacuum forming in advance is inserted into a cavity of aninjection molding die; and a film in-mold molding process in which abase resin is injection molded while a film having not been shaped isinserted into a cavity of an injection molding die. And there have beenproposed various methods for producing acrylic films suitable for thisapplication. For example, there are known a method in which the reducedviscosity of plastic polymer, the particle size of rubber-containingpolymer, the rubber content etc. are specified (Japanese PatentLaid-Open No. 8-323934) and a method in which the reduced viscosity ofacrylic polymer and the content of multi-layer structure acrylic polymerare specified (Japanese Patent Laid-Open Nos. 10-279766 and 10-306192).The films produced by these methods are known to excel in surfacehardness, transparency and moldability. However, these patentspecifications do not describe the problem of stress-whitening occurringin the films or cracks occurring at the time of film cutting.

For the problem of stress-whitening occurring in films, Japanese PatentLaid-Open No. 2002-80678 states that the problem can be solved byspecifying the particle size of rubber-like polymer used to be less than2000 Å. In this document, vacuum forming is performed at pre-heatingtemperatures as relatively high as 125 to 145° C.; however, some of thefilms described in the document undergoes stress-whitening atpre-heating temperature of 125° C. or 130° C. Stress-whitening is morelikely to occur at lower heating temperatures, and even by the methoddescribed in this document, a film is hard to form by vacuum forming attemperatures lower than the above described temperatures. This documentdoes not mention at all the problem of cracks occurring in a film whencutting the molding flash at the end portion of the film at finishingstep. Specifically, in any one of these films, when laminating the filmon a molded product of a complex shape at low temperatures, stress isconcentrated in the corner of the film, and the film is likely toundergo whitening, resulting in significant deterioration of its valueas a product. These films also have a problem of cracks caused whencutting at a finishing step the molding flash at the end portion of thefilm laminates obtained by a film insert molding process or film in-moldmolding process.

Under these circumstances, the present inventors directed tremendousresearch efforts toward the development of a film in whichstress-whitening hardly occur even by molding at low temperatures andcracks hardly occur at the time of cutting of the film. And they havefound that a film, composed of a resin composition that includes amulti-layer structure acrylic polymer using a special acrylic esterrubber-like polymer and a methacrylic polymer, undergoes lessstress-whitening even by molding at low temperatures and has highsurface hardness, excellent transparency, also excellent transparencyeven after heating and excellent weatherability, and its elongation atthe time of tensile breakage is high and its moldability, surfaceproperties and processability (cracks are less likely to occur at thetime of film cutting) are all excellent.

DISCLOSURE OF THE INVENTION

The present invention relates to an acrylic film composed of a resincomposition (C) that includes an acrylic graft copolymer (A) containingan acrylic ester rubber-like polymer and a methacrylic polymer (B)containing 80% by weight or more of methyl methacrylate, wherein

-   (1) the content of the acrylic ester rubber-like polymer in the    resin composition (C) is 5% by weight or more and 30% by weight or    less,-   (2) the average particle size of the acrylic ester rubber-like    polymer is 500 to 2000 Å,-   (3) the relationship between the average particle size d (Å) of the    acrylic ester rubber-like polymer and the amount w (% by weight) of    a crosslinking agent used in the acrylic ester rubber-like polymer    satisfies the following equation:    0.002d≦w≦0.005d,-   (4) the graft ratio of the acrylic graft copolymer (A) is 30% or    more and 200% or less, and-   (5) the reduced viscosity of methyl ethyl ketone soluble matter in    the resin composition (C) is 0.2 to 0.8 dl/g.

Preferably, the relationship between the average particle size d (Å) ofthe acrylic ester rubber-like polymer and the amount w (% by weight) ofthe crosslinking agent used in the acrylic ester rubber-like polymersatisfies the following equation:0.0025d≦w≦0.005d.

More preferably, the content of the acrylic ester rubber-like polymer inthe resin composition (C) is 15% by weight or more and 30% by weight orless.

Furthermore preferably, the content of the acrylic ester rubber-likepolymer in the resin composition (C) is more than 20% by weight and 30%by weight or less.

Preferably, the acrylic graft copolymer (A) is prepared by: graftpolymerizing a monomer mixture containing 86% by weight or more of amethacrylic ester onto the acrylic ester rubber-like polymer in a firststep; and graft polymerizing a monomer mixture containing 85% by weightor less of a methacrylic ester onto the resultant graft polymer in asecond step.

The present invention also relates to a laminate of the above acrylicfilm.

Preferably, the above laminate is produced by injection molding.

BEST MODE FOR CARRYING OUT THE INVENTION

The resin composition (C) used in the present invention includes anacrylic graft copolymer (A) containing an acrylic ester rubber-likepolymer and a methacrylic polymer (B) containing 80% by weight or moreof methyl methacrylate. The resin composition (C) can be obtained byfirst polymerizing the acrylic graft copolymer (A) and the methacrylicpolymer (B), separately, and then mixing the copolymer and the polymer.The preparation of these copolymer and polymer can be carried out in thesame reactor in such a manner as to first prepare the acrylic graftcopolymer (A) and subsequently prepare the methacrylic polymer (B). Thecopolymer (A) and the polymer (B) can be mixed in the form of latex,powder, beads or pellets.

The acrylic graft copolymer (A) used in the present invention isobtained by polymerizing a monomer mixture containing a methacrylicester as a chief ingredient in the presence of an acrylic esterrubber-like polymer (a cross linked rubber-like polymer containingacrylic ester as a chief ingredient).

The acrylic graft copolymer (A) used in the present invention can alsobe obtained by graft polymerizing a monomer mixture containing 86% byweight or more of a methacrylic ester in a first step and then graftpolymerizing a monomer mixture containing 85% or less of a methacrylicester in a second step, in the presence of an acrylic ester rubber-likepolymer.

The acrylic ester rubber-like polymer in the acrylic graft copolymer isprepared by polymerizing a monomer mixture including: 60 to 99% byweight of an acrylic ester; 0 to 30% by weight of anothercopolymerizable vinyl monomer and a specific amount of a copolymerizablecrosslinking agent. This preparation may be carried out by mixing allthe monomers or carried out in two or more steps while varying themonomer composition.

As the acrylic ester used, those having 1 to 12 carbon atoms in thealkyl group are preferable from the viewpoint of polymerizability andcost. Concrete examples of such acrylic esters include: methyl acrylate,ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylateand n-octyl acrylate. These monomers may be used alone or incombination.

The content of the acrylic ester in the acrylic ester rubber-likepolymer is preferably 60 to 99% by weight, more preferably 70 to 99% byweight, much more preferably 80 to 99% by weight and most preferably 85to 99% by weight. If the content is less than 60% by weight, the impactresistance tends to deteriorate, the elongation at the time of tensilebreakage also tends to be lowered, and cracks tend to occur at the timeof film cutting, whereas if the content is more than 99% by weight, thepencil hardness and transparency of the resultant film tend to belowered.

As the other copolymerizable vinyl monomer, methacrylic esters areparticularly preferable from the viewpoint of weathering resistance andtransparency. Concrete examples of methacrylic esters include methylmethacrylate, ethyl methacrylate, propyl methacrylate and butylmethacrylate. Aromatic vinyls (e.g. styrene, methylstyrene, etc.) andvinyl cyanideds (e.g. acrylonitrile, methacrylonitrile, etc.) are alsopreferable. These monomers may be used alone or in combination.

The content of the other copolymerizable vinyl monomer in the acrylicester rubber-like polymer is preferably 0 to 30% by weight and morepreferably 0 to 15% by weight. If the content is more than 30% byweight, the moldability, processability, transparency and surfaceproperties of the film tend to deteriorate.

As the copolymerizable crosslinking agent, conventional one maybe used.Concrete examples of such crosslinking agents include allylmethacrylate, allyl acrylate, triallyl cyanurate, triallyl isocyanurate,diallyl phthalate, diallyl malate, divinyl adipate, divinyl benzene,ethylene glycol dimethacrylate, diethylene glycol methacrylate,triethylene glycol dimethacrylate, trimethylolpropane trimethacrylate,tetramethylolmethane tetramethacrylate, dipropylene glycoldimethacrylate and the acrylates thereof. These crosslinking agents maybe used alone or in combination.

The content of the copolymerizable crosslinking agent in the acrylicester rubber-like polymer largely affects the average particle size ofthe acrylic ester rubber-like polymer and the stress-whitening,elongation at the time of tensile breakage and transparency of the film.Accordingly, it is important that the average particle size d (Å) of theacrylic ester rubber-like polymer and the content of the crosslinkingagent w (% by weight) satisfy the following equation:0.002d≦w≦0.005d.

The minimum of the average particle size of the acrylic esterrubber-like polymer is preferably 500 Å and more preferably 600 Å. Themaximum of the same is 2000 Å, preferably 1800 Å, more preferably 1600Å, much more preferably 1500 Å, and further more preferably 1200 Å. Ifthe average particle size is less than 500 Å, the impact resistance andelongation at the time of tensile breakage of the film tend todeteriorate and cracks tend to occur at the time of film cutting,whereas if the average particle size is more than 2000 Å,stress-whitening tends to occur in the resultant film, the transparencyof the film tend to be lowered, and the transparency of the film aftervacuum forming also tends to be lowered.

The content of the crosslinking agent is preferably in the range shownby the above equation, more preferably 0. 0025d≦w≦0.005d and much morepreferably 0.0025d≦w≦0.0045d. If the relationship between the content wof the crosslinking agent and the average particle size d of the acrylicester rubber-like polymer is in the range of 0. 002d>w or w>0.005d,stress-whitening tends to occur, the impact resistance and transparencyof the film tend to deteriorate, the elongation at the time of tensilebreakage tends to be lowered, cracks tend to occur at the time of filmcutting, and the processability of the film tends to deteriorate.

The acrylic graft copolymer (A) used in the present invention isobtained by polymerizing a monomer mixture containing a methacrylicester as a chief ingredient in the presence of the above describedrubber-like polymer. Preferably, the acrylic graft copolymer (A) isobtained by polymerizing 95 to 25 parts by weight of a monomer mixturecontaining a methacrylic ester as a chief ingredient in the presence of5 to 75 parts by weight of an acrylic ester rubber-like polymer in oneor more steps. The content of the methacrylic ester in the graftcopolymer composition (monomer mixture) is preferably 50% by weight ormore and more preferably 60% by weight or more. If the content is lessthan 50% by weight, the hardness and stiffness of the resultant filmtend to deteriorate.

The monomers used in the graft copolymerization include methacrylicesters and acrylic esters. And concrete examples of such monomersinclude those used in the above described acrylic ester rubber-likepolymer. These monomers may be used alone or in combination.

When intending to obtain the acrylic graft copolymer (A) is to beobtained by graft polymerization in two steps, the monomer mixturecontaining 86% by weight or more of a methacrylic ester is graftpolymerized in the presence of the above described acrylic esterrubber-like polymer in the first step and the monomer mixture containing85% by weight or less of a methacrylic ester is graft polymerized in thesecond step.

The content of the methacrylic ester in the monomer mixture graftpolymerized in the first step is preferably 86% by weight or more, morepreferably 88% by weight or more and most preferably 90% by weight ormore. The content of the methacrylic ester in the monomer mixture graftpolymerized in the second step is preferably 85% by weight or less, morepreferably 83% by weight or less and most preferably 80% by weight orless. If the content of the methacrylic ester in the monomer mixturegraft polymerized in the first step is less than 86% by weight and thatof the methacrylic ester in the monomer mixture graft polymerized in thesecond step is more than 85% by weight, stress-whitening is more likelyto occur, and therefore the contents in such ranges are not preferable.

Preferably, the acrylic graft copolymer (A) is obtained by polymerizing95 to 25 parts by weight of the monomer mixture containing a methacrylicester as a chief ingredient in the presence of 5 to 75 parts by weightof the acrylic ester rubber-like polymer in two or more steps. Thecontent of the monomer mixture polymerized in the presence of 5 to 75parts by weight of the acrylic ester rubber-like polymer is preferably90 to 5 parts by weight in each of the first and second steps and morepreferably 85 to 10 parts by weight in each of the first and secondsteps. If the amount is outside the above range, the transparency,pencil hardness, moldability and processability of the film tend todeteriorate. The content of a methacrylic ester in the graft copolymercomposition (monomer mixture) is preferably 50% by weight or more andmore preferably 60% by weight or more. If the content is less than 50%by weight, the hardness and stiffness of the resultant film tend todeteriorate.

When polymerizing the monomer mixture containing a methacrylic ester asa chief ingredient onto the acrylic ester rubber-like polymer, some ofthe monomer mixture does not undergo graft reaction with the acrylicester rubber-like polymer to produce an un-grafted polymer component.This component constitutes the whole or part of the methacrylic polymer(B). The graft copolymer is not dissolved in methyl ethyl ketone. Thelower limit of the graft ratio to the acrylic ester rubber-like polymeris 30%, preferably 50% and more preferably 80%. The upper limit of thegraft ratio is 200% and preferably 150%. If the graft ratio is less than30%, the transparency of the film and the elongation at the time oftensile breakage of the film tend to be lowered and cracks tend to occurat the time of film cutting, whereas if the graft ratio is more than200%, the melting viscosity at the time of film molding becomes high andthe moldability of the film tends to deteriorate.

The methacrylic polymer (B) used in the present invention containsmethyl methacrylate as a polymerizable ingredient. The content of methylmethacrylate is 80% by weight or more, preferably 90% by weight or moreand more preferably 92% by weight or more. If the content of methylmethacrylate is less than 80%, the hardness and stiffness of theresultant film tends to deteriorate.

The lower limit of the content of the acrylic ester rubber-like polymerin the resin composition (C) used in the present invention is preferably5% by weight, more preferably 10% by weight, much more preferably 15% byweight and most preferably more than 20% by weight. The upper limit ofthe content is preferably 30% by weight, more preferably 25% by weightand most preferably 23% by weight. If the content is less than 5% byweight, the elongation at the time of tensile breakage of the film tendstobe lowered, cracks are more likely to occur at the time of filmcutting and stress-whitening tends to occur in the film, whereas if thecontent is more than 30% by weight, the hardness and stiffness of theresultant film tend to deteriorate.

The reduced viscosity of the methyl ethyl ketone-soluble matter in theresin composition (C) used in the present invention is preferably 0.2 to0.8 dl/g and more preferably 0.2 to 0.7 dl/g. If the reduced viscosityis less than 0.2 dl/g, the elongation at the time of tensile breakage ofthe resultant film is lowered, cracks are likely to occur at the time offilm cutting, and the solvent resistance tends to deteriorate, whereasif the reduced viscosity is more than 0.8 dl/g, the moldability of thefilm tends to deteriorate.

The process for preparing the acrylic graft copolymer (A) andmethacrylic polymer (B) used in the present invention is notparticularly limited and, for example, emulsion polymerization,suspension polymerization and bulk polymerization are applicable.

In the emulsion polymerization, a conventional polymerization initiatoris used. Concrete examples of such initiators include: inorganicperoxides such as potassium persulfate and sodium persulfate; andorganic peroxides such as cumene hydroperoxide and benzoyl peroxide.Oil-soluble initiators such as azobisisobutyronitrile can also be used.These initiators may be used alone or in combination.

These initiators maybe used in combination with a reducing agent, suchas sodium sulfite, sodium thiosulfate, sodium formaldehyde, sulfoxylate,ascorbic acid or ferrous sulfate, as a conventional redox initiator.

The surfactant used in the emulsion polymerization is not particularlylimited, either, and any conventional surfactant for emulsionpolymerization can be used. Examples of such surfactants include:anionic surfactants such as sodium alkylsulfate, sodium alkylsulfonate,sodium alkylbenzenesulfonate, dioctyl sodium sulfosuccinate and sodiumlaurate; and nonionic surfactants such as reaction products of alkylphenols and ethylene oxide. These surfactants may be used alone or incombination.

The resin composition can be separated and collected from the polymerlatex obtained by the above described copolymerization through the stepsof conventional solidification and cleaning or through the treatment byspray drying or freeze-drying.

The resin composition (C) obtained in accordance with the presentinvention is particularly effective as a film and can be satisfactorilyprocessed by conventional melt extrusion techniques such as inflation orT die extrusion, or calendering, or solvent casting technique. Thethickness of the film is suitably about 30 to 500 μm and preferably 50to 300 μm. Films having more excellent surface properties can beobtained, if necessary, by bringing both sides of the film into contactwith a roll or a metal belt, particularly a roll or a metal belt heatedto temperatures above glass transition temperature at the time of filmmolding by using the resin composition (C).

To the resin composition (C) of the present invention, additives forcoloring, such as inorganic or organic pigments or dyes, or additivesfor stabilizing the film against heat or light, such as anti-oxidant,heat stabilizer, ultraviolet absorber or ultraviolet stabilizer, may beadded. These additives may be used alone or in combination.

The method of producing laminates using the film of the presentinvention is not limited to any specific one; however, such laminatesare preferably produced by a film insert molding process or filmin-molding molding process, like those described in Japanese PatentPublication Nos. 63-6339, 4-9647, Japanese Patent Laid-Open Nos. 7-9484,8-323934 and 10-279766. Specifically, laminates are produced by: firstinserting a film having been shaped in advance by vacuum forming etc. ora film having not been shaped into an injection molding die; closing theinjection molding die with the film held between the two parts of thedie to clamp the film; and injecting base resin into the molding die, sothat the film is molten on the surface of the molded part of the baseresin and integrated therewith. In the injection molding, the injectionmolding conditions such as resin temperature and injection pressure areproperly set taking the types of the base resin etc. into consideration.

The base resin that constitutes the acrylic laminates obtained inaccordance with the present invention is required to be able to melt andadhere to acrylic film. Examples of such base resins include ABS resin,AS resin, styrene resin, polycarbonate resin, vinyl chloride resin,acrylic resin, polyester resin, and resins containing these resins as achief ingredient.

EXAMPLES

In the following the present invention will be described by examples andcomparative examples; however, it should be understood that theseexamples are not intended to limit the present invention. The terms“parts” and “%” used in examples and comparative examples mean parts byweight and % by weight, respectively. The abbreviations used representthe following substances.

OSA: dioctyl sodium sulfosuccinate

BA: butyl acrylate

MMA: methyl methacrylate

CHP: cumene hydroperoxide

tDM: tert-dodecyl mercaptan

EA: ethyl acrylate

AMA: allyl methacrylate

The characteristics were obtained and the evaluation was made by thefollowing methods under the following conditions.

(Average Particle Size of Acrylic Ester Rubber-Like Polymer)

A film was subjected to ruthenium staining and observed with atransmission electron microscope. The particle size was measured for 500particles and the average value of the measurements was obtained (unit:Å).

(Graft Ratio G)

The powder prepared in reference examples was dissolved in methyl ethylketone and the insoluble matter was separated from the soluble matter.The insoluble matter was taken as graft polymer and the graft ratio wasobtained by the following equation (unit: %):

G=(weight of insoluble matter−weight of rubber-like polymer)/weight ofrubber-like polymer×100.

(Reduced Viscosity)

The powder prepared in reference examples was dissolved in methyl ethylketone and the insoluble matter was separated from the soluble matter.The soluble matter was dissolved in N,N-dimethyl formamide so that thecontent of the soluble matter was 0.3% by weight. The viscosity at 30°C. was measured using an Ubbelohde tube (unit: dl/g).

(Tensile Strength, Elongation at the Time of Tensile Breakage)

Film was cut out in JIS dumbbell shape, and the tensile strength andelongation at the time of tensile breakage of the dumbbell specimen weremeasured with Autograph (Shimadzu) at 23° C. at a tensile speed of 50mm/min (unit: tensile strength MPa, elongation at the time of tensilebreakage %).

(Stress-Whitening)

An operation was performed once at 23° C. in which film (100 μm thick,cut to 210 mm×290 mm) was folded in two and held down firmly withfingers to give it a fold. Then the whitening occurring on the film wasobserved and evaluated based on the following criteria.

-   ◯: No whitening is observed on the fold.-   Δ: Opaque white (slight whitening) is observed on part of the fold.-   ×: Whitening is significant.    (Transparency)

The haze of film was measured in accordance with JIS K 6714 (unit: %).

(Transparency After Heating)

The haze of film was measured in accordance with JIS K 6714 afterheating the film at 160° C. for 1 minute, and the difference in hazebefore and after heating was evaluated based on the following criteria.

-   ◯: The difference in haze before and after heating is less than 0.5.-   Δ: The difference in haze before and after heating is 0.5 or more    and less than 1.0.-   ×: The difference in haze before and after heating is 1.0 or more.    (Pencil Hardness)

The pencil hardness of film was measured in accordance with JIS K 5400.

(Moldability of Film)

Film molding was performed continuously for 3 hours under the sameconditions as those of examples 1 to 17 and comparative examples 1 to 7and the state of molding was observed (the center portion of film wascut off every 15 minutes to measure the thickness of the film). Themoldability was evaluated based on the following criteria.

-   ◯: The thickness of film is uniform (100±5 μm) and film can be    molded without causing film breakage.-   Δ: The thickness of film is almost uniform (100±10 μm) and film can    be molded without causing film breakage.-   ×: The thickness of film is not uniform and film breaks.    (Surface Properties of Film)

The surface of a film 1 m×1 m in size (100 μm thick) was observed andthe surface properties were judged by the standards for fish eye, dieline and carbonized resin which were used as a base for acceptance ofthe film.

The standard for fish eye used as a base for acceptance of film is thatthe number of fish eyes observed is 1000 or less and the term“significant” means that the number of fish eyes observed is 10,000 ormore.

The standard for die line used as a base for acceptance of film is thatthe number of die lines less than 10 cm long is 5 or less and the term“significant” means that die line 1 m or more long is observed.

The standard for carbonized resin used as a base for acceptance of filmis that the film is not discolored or the number of carbonized resinobserved is 5 or less and the term “significant” means that carbonizedresin is obvious and the number of carbonized resin is 50 or more.

-   ◯: The surface of film satisfies the standards for all of the above    3 items.-   Δ: The surface of film does not satisfy the standard for only one    item, but the evaluation for the rejected item is not “significant”.-   ×: The surface of film does not satisfy the standards for two or    more of the above 3 items, or it is evaluated as “significant” for    any one of the above 3 items.    (Processability of Film)

Film (100 μm thick) was placed on a flat stand and cut to 20 cm invarious directions with a cutter knife (with an edge 0.38 mm thick)using force sufficient to cut the film and the processability of thefilm was evaluated based on the following criteria.

-   ◯: No crack was observed.-   Δ: Cracks were observed (less than 5 cracks which were 5 mm or less    long).-   ×: Cracks were significantly observed (5 or more cracks which were 5    mm or less long, or at least one crack 5 mm or more long was    observed).

Reference Examples 1 to 18

The following substances were fed to an 8 L polymerizer fitted with astirrer. Water 200 parts OSA 0.2 parts Disodiumethylenediaminetetraacetate 0.001 parts Ferrous sulfate 0.00025 partsSodium formaldehydesulfoxylate 0.15 parts

After deoxidizing the inside of the polymerizer and heating the same to60° C., the monomer mixture (a) shown in Table 1 and Table 2 was addeddropwise successively at a rate of 10 parts/hour and polymerized for 30minutes to obtain an acrylic ester rubber-like polymer. The degree ofpolymerization conversion was 99.5%. Then, after feeding 0.2 parts ofOSA, and the monomer mixture (b) shown in Table 1 and Table 2 was addeddropwise successively at a rate of 12 parts/hour and polymerized for 1hour to obtain an acrylic graft copolymer (A) and a methacrylic polymer(B). The resultant latex was salted out and solidified with calciumacetate, rinsed and dried to obtain resin powder. The reduced viscosityand graft ratio of the resin powder were measured. The results are shownin Table 1 and Table 2.

Reference Example 19

A monomer mixture of 92% of MMA and 8% of BA was subjected to emulsionpolymerization to prepare a copolymer. The reduced viscosity of theresultant methacrylic ester copolymer was 0.36 dl/g.

Reference Example 20

MMA-EA copolymer (Sumipex EX by Sumitomo Chemical: a copolymerconsisting of about 95% of MMA and about 5% of EA, reduced viscosity0.30 dl/g) prepared by suspension polymerization was used. TABLE 1Reference Example 1 2 3 4 5 6 7 8 9 OSA (parts) 0.20 0.24 0.18 0.28 0.350.20 0.15 0.05 0.20 Monomer (parts) 21 23 23 30 40 14 18 30 23 mixtureBA (%) 90 90 90 90 90 98 90 90 90 (a) MMA (%) 7.6 8.0 7.5 6.5 8.0 — 7.07.5 8.6 AMA (%) 2.4 2.0 2.5 3.5 2.0 2.0 3.0 2.5 1.4 CHP (parts) 0.060.08 0.08 0.09 0.12 0.05 0.05 0.09 0.06 Monomer (parts) 79 77 77 70 6086 82 70 77 mixture BA (%) 10 10 10 10 10 10 10 10 10 (b) MMA (%) 90 9090 90 90 90 90 90 90 CHP (parts) 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.300.30 tDM (parts) 0.30 0.28 O.25 0.25 0.28 0.25 0.30 O.30 O.60 Reduced0.35 0.32 0.36 0.39 0.36 0.38 0.34 0.28 0.15 viscosity Graft ratio 135130 120 165 90 110 110 115 28

TABLE 2 Reference Example 10 11 12 13 14 15 16 17 18 OSA (parts) 0.200.15 O.24 0.28 0.26 0.26 0.20 0.20 0.26 Monomer (parts) 16 18 14 30 3030 16 16 30 mixture BA (%) 90 90 98 90 89 89 90 90 89 (a) MMA (%) 7.67.4 — 7.5 8.0 7.5 9.0 8.6 8.0 AMA (%) 2.4 2.6 2.0 2.5 3 3.5 1.0 2.4 3.0CHP (parts) 0.06 0.06 0.05 0.09 0.09 0.09 0.06 0.06 0.09 Monomer (parts)84 82 86 70 70 70 84 84 70 mixture BA (%) 10 10 10 10 8 8 10 10 8 (b)MMA (%) 90 90 90 90 92 92 90 90 92 CHP (parts) 0.30 0.30 0.30 0.30 0.300.30 0.30 0.30 0.30 tDM (parts) 0.28 0.30 0.25 0.25 0.25 0.25 0.28 0.600.30 Reduced 0.35 0.32 0.38 0.32 0.39 0.39 0.34 0.15 0.33 viscosityGraft ratio 135 140 125 120 150 165 110 28 125

Examples 1 to 17 and Comparative Examples 1 to 7

Film was prepared in the following procedures using resin powdersobtained in reference examples 1 to 20.

1.5 parts of TINUVIN 1577 (Ciba Specialty Chemicals Inc.) as a UVabsorber and 0.3 parts of Sumilizer GM (Sumitomo Chemical) as anantioxidant were mixed into 100 parts of the resin composition of theformulation shown in Table 3 and Table 4 and extruded with a ventedextruder at 220° C. to obtain extruded pellets. The resultant pelletswere molded with a T-die extruder at die temperature of 240° C. toobtain film 100 μm thick. Various physical properties were evaluatedusing this film. The results are shown in Table 3 and Table 4. TABLE 3Examples 1 2 3 4 5 6 7 8 9 10 11 12 13 Resin Reference 100 compo-example 1 sition Reference 100 example 2 Reference 100 example 3Reference 70 80 example 4 Reference 60 example 5 Reference 100 example 6Reference 100 example 7 Reference example 8 Reference example 9Reference 100 example 10 Reference 100 example 11 Reference 100 example12 Reference 60 50 example 13 Reference example 14 Reference example 15Reference example 16 Reference example 17 Reference example 18 Reference20 50 example 19 Reference 30 40 40 example 20 Average particle 800 6001200 780 780 800 800 800 800 1200 600 780 780 size (Å) of rubber-likepolymer Amount of 2.4 2.0 2.5 3.5 3.5 2.0 2.0 3.0 2.4 2.6 2.0 2.5 2.5crosslinking agent (parts) Content of 21 23 23 21 24 24 14 18 16 18 1418 15 rubber-like polymer (%) Graft ratio (%) 135 130 120 165 165 90 110110 135 140 125 120 120 Reduced viscosity 0.35 0.32 0.36 0.39 0.37 0.360.38 0.34 0.35 0.32 0.38 0.31 0.34 (dl/g) Tensile strength 55 57 54 6050 51 76 63 65 61 71 62 68 (MPa) Elongation at the 100 90 120 100 120100 50 70 70 80 60 65 60 time of tensile breakage (%) Stress-whitening ∘∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ Δ ∘ ∘ ∘ Transparency 0.6 0.4 0.9 0.6 0.6 0.8 0.3 0.5 0.30.6 0.3 0.4 0.3 (haze) (%) Transparency ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ afterheating Pencil hardness H H H H H H 2H H H H 2H H H Moldability of ∘ ∘ ∘∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ film Surface ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ properties offilm Processability of ∘ ∘ ∘ ∘ ∘ ∘ Δ Δ Δ ∘ Δ ∘ ∘ film

TABLE 4 Examples Comparative examples 14 15 16 17 1 2 3 4 5 6 7 ResinReference compo- example 1 sition Reference example 2 Reference example3 Reference example 4 Reference 100 example 5 Reference example 6Reference example 7 Reference 70 60 10 example 8 Reference 100 example 9Reference example 10 Reference example 11 Reference example 12 Reference100 example 13 Reference 60 example 14 Reference 60 example 15 Reference100 example 16 Reference 100 example 17 Reference 60 example 18Reference 40 40 90 example 19 Reference 40 30 40 example 20 Averageparticle 800 800 780 780 2500 800 800 800 2500 2500 810 size (Å) ofrubber-like polymer Amount of crosslinking 3.0 3.5 2.5 3.0 2.5 1.4 2.01.0 2.5 2.5 2.4 agent (parts) Content of rubber-like 18 18 30 18 21 2340 16 18 3 16 polymer (%) Graft ratio (%) 150 165 90 125 115 28 90 110115 115 28 Reduced viscosity 0.39 0.39 0.32 0.32 0.28 0.15 0.36 0.330.29 0.35 0.15 (dl/g) Tensile strength (MPa) 62 61 32 62 48 25 35 58 5480 28 Elongation at 65 65 100 20 50 5 150 60 50 5 1 the time of tensilebreakage (%) Stress-whitening ∘ ∘ ∘ ∘ x x ∘ x x x x Transparency 0.3 0.30.9 0.6 2.5 1.2 1.5 0.8 2.3 3.5 2.9 (haze) (%) Transparency ∘ ∘ ∘ ∘ x xΔ Δ x Δ x after heating Pencil hardness H H B H H H 3B H H 3H HBMoldability of film ∘ ∘ ∘ ∘ ∘ x ∘ ∘ ∘ x x Surface properties of ∘ ∘ Δ ∘∘ x ∘ Δ ∘ Δ x film Processability of film ∘ ∘ ∘ ∘ ∘ x ∘ ∘ Δ x x

Reference Examples 21 to 28

The following substances were fed to an 8 L polymerizer fitted with astirrer. Water 200 parts OSA 0.2 parts Disodiumethylenediaminetetraacetate 0.001 parts Ferrous sulfate 0.00025 partsSodium formaldehydesulfoxylate 0.15 parts

After deoxidizing the inside of the polymerizer and heating the same to60° C., the monomer mixture (a) shown in Table 5 was added dropwisesuccessively at a rate of 10 parts/hour and polymerized for 30 minutesto obtain an acrylic ester rubber-like polymer. The degree ofpolymerization conversion was 99.5%. Then, after feeding 0.2 parts ofOSA, and the monomer mixture (b) shown in Table 5 was added dropwisesuccessively at a rate of 12 parts/hour in first and second steps andpolymerized for 1 hour to obtain an acrylic graft copolymer (A) and amethacrylic polymer (B). The resultant latex was salted out andsolidified with calcium acetate, rinsed and dried to obtain resinpowder. The reduced viscosity and graft ratio of the resin powder weremeasured. The results are shown in Table 5. TABLE 5 Reference examples21 22 23 24 25 26 27 28 OSA (parts) 0.20 0.26 0.24 0.26 0.15 0.20 0.050.20 Monomer (parts) 18 30 16 30 30 16 30 16 mixture BA (%) 90 90 9796.2 89 90 90 90 (a) MMA (%) 7.4 7.5 — — 8 9 7.5 8.6 AMA (%) 2.6 2.5 3.03.8 3.0 1.0 2.5 1.4 CHP (parts) 0.06 0.09 0.05 0.09 0.09 0.05 0.09 0.06Monomer First step (parts) 42 40 50 35 30 54 35 44 mixture BA (%) 12 1010 10 8 20 10 10 (b) MMA (%) 88 90 90 90 92 80 90 90 CHP (parts) 0.150.15 0.21 0.15 0.13 0.15 0.15 0.15 tDM (parts) 0.15 0.13 0.21 0.15 0.110.18 0.16 0.30 Second step (parts) 40 30 20 35 40 30 35 40 BA (%) 17 2020 20 30 10 20 20 MMA (%) 83 80 80 80 70 90 80 80 CHP (parts) 0.15 0.150.09 0.15 0.17 0.15 0.15 0.30 tDM (parts) 0.15 0.12 0.09 0.15 0.14 0.100.16 0.15 Reduced viscosity 0.35 0.39 0.30 0.32 0.39 0.34 0.28 0.15Graft ratio 135 145 140 120 150 110 115 28

Examples 18 to 24 and Comparative Examples 8 to 10

Film was prepared using each of the resin powders obtained in referenceexamples 19 to28 through the following procedure.

1.5 parts of TINUVIN 1577 (Ciba Specialty Chemicals Inc.) as a UVabsorber and 0.3 parts of Sumilizer GM (Sumitomo Chemical) as anantioxidant were mixed into 100 parts of the resin composition of theformulation shown in Table 6 and extruded with a vented extruder at 220°C. to obtain extruded pellets. The resultant pellets were molded with aT-die extruder at die temperature of 240° C. to obtain film 100 μmthick. Various physical properties were evaluated using this film. Theresults are shown in Table 6. TABLE 6 Examples Comparative examples 1819 20 21 22 23 24 8 9 10 Resin Reference 50 90 compo- example 19 sitionReference 40 40 30 example 20 Reference 100 example 21 Reference 60 100example 22 Reference 100 example 23 Reference 60 50 example 24 Reference70 example 25 Reference 100 example 26 Reference 10 example 27 Reference100 example 28 Average particle 800 780 600 780 1200 780 780 800 2500800 size (Å) of rubber-like polymer Amount of crosslinking 2.6 2.5 3.03.8 3.0 3.8 2.5 1.0 2.5 1.4 agent (parts) Content of rubber-like 18 1816 18 21 15 30 16 3 16 polymer (%) Graft ratio (%) 135 145 140 120 150120 145 110 115 28 Reduced viscosity 0.35 0.35 0.30 0.31 0.37 0.34 0.390.34 0.35 0.15 (dl/g) Tensile strength (MPa) 61 63 65 62 55 67 32 70 8568 Elongation at 70 68 90 100 110 95 110 50 15 10 the time of tensilebreakage (%) Stress-whitening ∘ ∘ ∘ ∘ ∘ ∘ ∘ x x x Transparency (haze)(%) 0.6 0.5 0.4 0.6 0.8 0.5 0.9 0.8 3.5 2.6 Transparency ∘ ∘ ∘ ∘ ∘ ∘ ∘ Δx x after heating Pencil hardness H H H H F 2H 2B H 3H HB Moldability offilm ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ Δ x Surface properties of ∘ ∘ ∘ ∘ ∘ ∘ Δ Δ x x filmProcessability ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ x x of film

INDUSTRIAL APPLICABILITY

According to the present invention, a film can be obtained whichundergoes less stress-whitening even by molding at low temperatures,which has high surface hardness, excellent transparency, also excellenttransparency even after heating and excellent weatherability, whoseelongation at the time of tensile breakage is high, and whosemoldability, surface properties and processability (cracks are lesslikely to occur at the time of film cutting) are all excellent.

1. An acrylic film, composed of a resin composition (C) that comprisesan acrylic graft copolymer (A) containing an acrylic ester rubberpolymer and a methacrylic polymer (B) containing 80% by weight or moreof methyl methacrylate, wherein (1) the content of the acrylic esterrubber polymer in the resin composition (C) is 5% by weight or more and30% by weight or less, (2) the average particle size of the acrylicester rubber polymer is 500 to 2000 Å, (3) the relationship between theaverage particle size d (Å) of the acrylic ester rubber polymer and theamount w (% by weight) of a crosslinking agent used in the acrylic esterrubber polymer satisfies the following equation:0.002d≦w≦0.005d, (4) the graft ratio of the acrylic graft copolymer (A)is 30% or more and 200% or less, and (5) the reduced viscosity of methylethyl ketone soluble matter in the resin composition (C) is 0.2 to 0.8dl/g.
 2. The acrylic film according to claim 1, wherein the relationshipbetween the average particle size d (Å) of the acrylic ester rubberpolymer and the amount w (% by weight) of the crosslinking agent used inthe acrylic ester rubber polymer satisfies the following equation:0.0025d≦w≦0.005d.
 3. The acrylic film according to claim 1 or 2, whereinthe content of the acrylic ester rubber polymer in the resin composition(C) is 15% by weight or more and 30% by weight or less.
 4. The acrylicfilm according to claim 1 or 2, wherein the content of the acrylic esterrubber polymer in the resin composition (C) is more than 20% by weightand 30% by weight or less.
 5. The acrylic film according to claim 1 or2, wherein the acrylic graft copolymer (A) is prepared by: graftpolymerizing a monomer mixture containing 86% by weight or more of amethacrylic ester onto the acrylic ester rubber polymer in a first step;and graft polymerizing a monomer mixture containing 85% by weight orless of a methacrylic ester onto the resultant graft polymer in a secondstep.
 6. A laminate containing the acrylic film according to claim 1 or2.
 7. The laminate according to claim 6, produced by injection molding.